CAIRO, Egypt — Iraq's prime minister said Sunday that he has ordered a halt to the U.S. military construction of a barrier separating a Sunni enclave from surrounding Shiite areas in Baghdad after fierce criticism over the project at home.

The challenge to the U.S. initiative came as Prime Minister Nouri al-Maliki began a regional tour to shore up support from mostly Sunni Arab nations for his Shiite-dominated government as sectarian violence persists despite a nearly 10-week-old security crackdown.

The U.S. military announced last week that it was building a three-mile-long and 12-foot-tall concrete wall in Azamiyah, a Sunni stronghold in northern Baghdad whose residents have often been the victims of retaliatory mortar attacks by Shiite militants following bombings usually blamed on Sunni insurgents.

U.S. and Iraqi officials defended plans for the barrier as an effort to protect the neighborhood, but residents and Sunni leaders complained it was a form of discrimination that would isolate the community. A large protest was scheduled for Monday in the area.

In his first public comments on the issue, al-Maliki said Sunday that he had ordered the construction to stop.

"I oppose the building of the wall and its construction will stop," al-Maliki said during a joint news conference with the secretary-general of the Arab League. "There are other methods to protect neighborhoods, but I should point out that the goal was not to separate, but to protect."